Effects of Fe-Mn modified biochar on rice Cd uptake and soil microbial community
In this study,the effects of Fe-Mn modified biochar(BCFM)on rice Cd uptake and soil microbial community structure were further studied through pot experiments.The results showed that BCFM could effectively reduce the Cd uptake in rice and change the soil microbial community structure.As compared with the control,the content of soil organic matter,soil cation exchange capacity,soil total Fe,and total Mn were slightly changed with the application of 0.5~2g/kg BCFM.However,the content of soil organic matter,cation exchange capacity,total Fe and Mn were increased significantly(P<0.05)by 13.6%,13.58%,5.0%,and 12.1%,respectively,with the application of 4g/kg BCFM.Meanwhile,the content of available Cd in soil decreased significantly(P<0.05)by 67.9%,and the content of Cd in stems,leaves,and brown rice decreased significantly(P<0.05)by 74.3%,44.9%,and 84.9%,respectively.The relative abundance of Firmicutes and Proteobacteria at the phylum level in rice rhizosphere soil was increased with the application of BCFM,while the relative abundance of Bacteroidota,Patescibacteria,Desulfobacterota,and Nitrospirae was decreased.Heatmap analysis showed that BCFM could promote the relative abundance of Bacillus,Citrifermentans,Geobacter,and Desulfovibrio,which were involved in iron-manganese redox and sulfate reduction in rice rhizosphere soil.Redundancy analysis and network analysis showed that BCFM could promote positive interaction of soil microorganisms by affecting soil total Fe,organic matter,and available Cd content.Therefore,BCFM could be used as an effective and ecological safe passivator for the remediation of Cd-contaminated paddy soil.
Fe-Mn modified biocharriceCd uptakemicrobial community structureiron-manganese redox bacteria